spec: simple_cov spec_helper formatter tweak

Change-Id: I967eeb8554d0d7355000d691fbb68e1452f6cc21
Reviewed-on: https://gerrit.instructure.com/23190
Reviewed-by: Shawn Meredith <shawn@instructure.com>
Product-Review: Shawn Meredith <shawn@instructure.com>
QA-Review: Shawn Meredith <shawn@instructure.com>
Tested-by: Shawn Meredith <shawn@instructure.com>

spec/spec_helper.rb

@@ -18,7 +18,7 @@
 if ENV['COVERAGE'] == "1"
   puts "Code Coverage enabled"
   require 'simplecov'
-  SimpleCov.start('rails') do
+  SimpleCov.start do
     SimpleCov.formatter = SimpleCov::Formatter::HTMLFormatter
     add_filter '/spec/'
     add_filter '/config/'